Geometric Calculations for the Spiral Heat Exchanger

The present paper deals with the calculation methods for semicircled spirals, from which are derived the geometric calculating formulas for spiral heat exchangers. This series of formulas are characterized by their universality, accuracy, and convenience.     

Heat Exchanger Network synthesis with Detailed Heat Exchanger Design

Pressure drop and fouling are important issues in heat exchanger network synthesis, which are usually neglected. Heat exchangers were designed in detail during the heat exchanger network synthesis, and pressure drop and fouling effects were taken into account. Pinch analysis combined with exergoeconomic analysis was used for determining optimal minimum approach temperature (ΔT_min) for heat exchanger network synthesis. Exergy consumption of heat transfer in HENs was calculated using a subsection integral on balanced composite curves. The heat transfer coefficients of all heat exchangers in the network were calculated iteratively to meet the requirements of optimal area and allowable pressure drops. The proposed method was applied to an industrial case. Numerical results indicate the importance of the detailed design of heat exchangers in HENs synthesis.     

Flow and Heat Transfer Prediction in a Corrugated Plate Heat Exchanger using a CFD Code

The purpose of this study is to explore the potential of using a general purpose CFD code to compute the characteristics of the flow field, and of the heat transfer augmentation in conduits with corrugated walls, encountered in commercial plate heat exchangers (PHE). The CFD code is used to simulate the performance of a PHE model comprised of stainless steel plates, following a herringbone design and assembled for single‐pass countercurrent flow. The code is validated by comparing the numerical results with experimental data on pressure drop and overall temperature differences acquired for the countercurrent flow of water at both sides of the model PHE. The limited data published in the literature are also in fairly good agreement with the results of the present study. It is shown that the CFD code is an effective and reliable tool for studying the effect of various geometrical configurations on the optimum design of a PHE.     

管式换热器化学清洗实例

以某厂管式换热器清洗为例,以清除换热器中有机物以及水垢为目的,对换热器进行清洗.用碱液脱脂,用柠檬酸,缓蚀剂作为清洗剂除垢.按照一定的工序进行,介绍了清洗的方法和工艺条件,例证了管式换热器的化学清洗工艺.     

Vapor Condensation Heat Transfer in a Thermoplate Heat Exchanger

The heat transfer and pressure drop in a thermoplate heat exchanger operating as a condenser have been investigated experimentally. In order to separate the heat transfer resistances in the condensation process, the single phase forced convection has been studied using distilled water and Marlotherm oil in the thermoplate and correlations developed for the Nusselt number and the friction factor. For the condensation experiments, an apparatus has been constructed comprising two identical condensers composed of the same thermoplate type as employed in the single phase experiments. Isopropanol is used as a test fluid at pressures below atmospheric pressure. The heat transfer resistances in the condensation experiments are separated and expressions for the condensation heat transfer and pressure drop are developed with the aid of the results obtained in the single phase studies.     

Non‐Newtonian Heat Transfer on a Plate Heat Exchanger with Generalized Configurations

For the configuration optimization of plate heat exchangers (PHEs), the mathematical models for heat transfer and pressure drop must be valid for a wide range of operational conditions of all configurations of the exchanger or the design results may be compromised. In this investigation, the thermal model of a PHE is adjusted to fit experimental data obtained from non‐Newtonian heat transfer for eight different configurations, using carboxymethylcellulose solutions (CMC) as test fluid. Although it is possible to successfully adjust the model parameters, Newtonian and non‐Newtonian heat transfer cannot be represented by a single generalized correlation. In addition, the specific heat, thermal conductivity and power‐law rheological parameters of CMC solutions were correlated with temperature, over a range compatible with a continuous pasteurization process.     

Straightforward Solutions of Heat Exchanger Network (HEN) Problems

Advantage is taken of an unused potential which lies in the evolutionary development method for heat exchanger networks (HEN) proposed by Linnhoff and Flower to construct an algorithm which reduces recursively the number of units of a given HEN problem. As a result, all networks are generated that fulfill the heating and cooling requirements of the problem and whose number of units cannot be further reduced. Among the solutions obtained, those are selected which satisfy the condition of minimum permissible temperature driving force. A C++ implementation of the algorithm has been applied to a number of problems taken from the literature.     

换热设备多相流防除垢新技术的研究进展

对换热设备多相流防、除垢技术的研究及应用情况进行了回顾和综合分析 ,提出了多相流防、除垢技术仍需解决的几个关键问题 ,为进一步的研究指出了方向     

Escherichia coli Biofilm Characteristics on Polymeric Heat Exchanger Surfaces

Time‐dependent effects on the apparent roughness and surface free energy of different polymeric surfaces and stainless steel were studied during the biofouling process for Escherichia coli K12. The surface roughness increases during primary adhesion of E. coli on the surfaces and is later reduced as the surface between scattered bacteria is completely covered, forming a uniform biofilm. During the fouling process, the polar fraction of the surface free energy significantly increased, whereas the dispersive fraction decreased for all substrates. The attachment of E. coli and subsequent bacterial production of extracellular polymeric substances increased the polarity of the initially nonpolar polymeric surfaces to increase wettability.     

Simulation Analysis of the Heat Transfer Performance of an N-type Microchannel Heat Exchanger

A microchannel heat exchanger with a triangular wave and symmetrical triangular wave structure was proposed in this paper. In addition, a new N-type microchannel heat exchanger was developed to balance the heat transfer performance and pressure drop. The relationship between different configurations of the N structure of the microchannel and the heat transfer performance was analyzed. The results showed that, at a high inlet flow rate, the symmetrical triangular wave microchannel had the best heat transfer performance, followed by the triangular wave microchannel and the straight channel. At the same flow rate, the degree of disturbance of the fluid was highest in the symmetrical N-structure microchannel, and an excellent heat transfer effect was observed.     

换热器管子拉脱的分析与对策

分析了一台固定管板式换热器运行工况变化引起管子拉脱的原因,并提出改进方案。     

双波纹板管式换热器流场的数值模拟

介绍了一种用于气气交换的错流式双波纹板管式换热器,它具有单位体积换热面积大,结构紧凑、稳定性好以及换热系数高等特点.运用Fluent软件.对不同尺寸的双波纹板管式换热器的流场进行了模拟,经过分析对比得到换热效果最佳时双波纹板片的形状.研究结果表明,换热板片上双波纹的波幅、周期和板间距决定了板式换热器的换热效果和压降等.     

Numerical Simulation of Fluid Flow and Heat Transfer in Thermoplates

A thermoplate is a heat transfer device consisting of two metallic sheets that are spot‐welded according to an appropriate pattern over the whole surface area whereas the edges – except for connecting tubes – are continuously seam‐welded. By applying a hydro‐form technique, a channel having a complex geometry is established between the sheets. Such heat transfer devices are encountered in several areas of cooling and heating techniques and process technology, e.g. as condensers or evaporators. The objective of the described investigations was to numerically obtain the optimal geometry of the thermoplate with respect to heat transfer of the inside fluid that passes through the channel as a single phase. The numerical experiments show that the heat transfer potential of the thermoplate having a staggered arrangement of welding spots is markedly higher than that of a common flat channel, particularly at larger Reynolds numbers. The variations of the geometrical parameters show the potential for the heat transfer improvement in comparison to a corresponding parallel plate channel.     

A Method for Flexible Heat Exchanger Network Design under Severe Operation Uncertainty

Most investigations on heat exchanger network (HEN) synthesis which plays an important role in improving the efficiency of industrial plants, focus on deterministic conditions whereas operational flexibility and feasibility are less concerned. In the real industrial world, each system experiences various disturbances due to changes in stream temperature, flow rate, and other uncertain factors. An approach for flexible HEN synthesis under severe operation uncertainty is proposed, which is represented by the Probability bounds analysis (PBA) theory and is sampled by a double‐loop sampling method. A case study, which generates a better solution with less total annual cost and good flexibility under severe uncertainty, demonstrates the capability of this simplified approach.     

Heat Exchanger Network Integration Considering Flow Exergy Loss

This work describes a systematic procedure to integrate a heat exchanger network (HEN) considering heat and flow exergy consumptions. The flow exergy consumption by the HEN is calculated by means of pressure drop correlation and stepwise optimization. Case studies reveal that the flow exergy loss changes the two‐way trade‐off between the operating cost and the capital cost in the traditional method. The introduction of heat exergy loss adds the weight of energy cost by considering both the external utility consumption and internal heat exergy loss in the HEN, which benefits heat recovery and energy conservation at the cost of more area and investment. In contrast, the flow exergy loss shifts the balance to the capital cost by adding the cost relating to area in terms of flow frictional dissipation.     

水平管内油气两相混合物的传热计算

随着油气田开发的不断深入,油气两相混输技术的使用越来越广泛,这就涉及到水平管内油气两相混合物的传热计算问题。鉴于水平管内油气两相流动的复杂性,以三种常用简化计算的假设为基础,分别建立均相传热模型、分相传热模型以及流型传热模型,同时运用Aspen EDR软件对油气两相传热进行计算。将计算结果与工程实际设计值进行对比分析可知,均相传热模型与实际值相差最大;而流型传热模型最接近实际值,其相对误差仅2.6%;分相传热模型与软件计算值误差则介于这两者之间。另外,通过改变流速,对各个模型得出的油气两相传热系数进行了对比分析。     

改进的无分流换热器网络最优综合法

提出了不分流换热网络改进的同步最优综合混合整数非线性规则模型，通过引入处理带０－１整型变量的规则，提出了采用非线性规划求解换网络综合ＭＩＮＬＰ问题的方法，只需求解ＮＬＰ问题就可得到连续变量和０－１变量同步优化的网络结果。算例表明，该模型和方法是有效的。     

振荡流热管研究现状及在干燥系统中的应用研究

对振荡流热管及振荡流热管换热器研究现状进行了分析,并时振荡流热管换热器用于干燥余热回收系统进行了研究。结果表明,自激振荡流热管是一种高效的传热元件,利用这种热管研制出的高效换热器完全适用于干燥尾气的余热回收。     

换热器检修过程中换热管查漏方法新技术

石油化工行业对各类换热器的应用非常广泛。在使用过程中泄露问题时有发生,处理泄漏方法很多,也很成熟,但是,查漏工作始终困扰着业内人士。目前各企业均是在工装设计上投入了大量的精力,虽然取得了一定的效果,但都不够理想。因为均未摆脱繁重的体力劳动和笨重的工装卡具。通过反复实践和论证,确定利用单管抽真空代替水压试验对换热管查漏技术具备可行性;该施工方法通过了2007-2008年度的石油工法评审(省部级),题目为;利用抽真空的方法代替水压试验。并申请取得了持有专利技术的专用工具(换热器查漏用真空枪——专利号200810228742)。